A fuel cell (such as polymer electrolyte type fuel cell) allows a fuel gas containing hydrogen and an oxidant gas containing oxygen such as air to electrochemically react with each other, such that electric power and heat are produced at the same time.
In general, a fuel cell is configured by stacking a plurality of cells, and pressurizing and fastening them with a bolt. One cell is configured such that a membrane-electrode assembly (hereinafter, referred to as the MEA) is sandwiched by one paired plate-like conductive separators. A circumferential region of the MEA is held by a frame. In addition, here, the MEA having the frame is referred to as the electrode-membrane-frame assembly.
The electrode-membrane-frame assembly is formed as follows in general (refer to International Publication No. WO2009/072291, for example). FIGS. 26A to 26C are schematic explanatory views showing production steps of a conventional electrode-membrane-frame assembly in which a connection part between a MEA and a frame is overdrawn.
First, as shown in FIG. 26A, a molten thermoplastic resin is poured into a die T100A to form a primary molded body 102A serving as one part of a frame 102 by injection molding.
Then, as shown in FIG. 26B, a MEA 101 is arranged on the primary molded body 102A.
Here, the MEA 101 is configured by a polymer electrolyte membrane 111, and one paired electrode layers 112 arranged on both surfaces of the polymer electrolyte membrane ill. In general, each electrode layer 112 is configured by a catalyst layer 113 containing, as its principal component, carbon powder bearing a metal catalyst, and a porous gas diffusion layer 114 having conductivity and arranged on the catalyst layer 113.
Then, as shown in FIG. 26C, a molten thermoplastic resin is poured into a die T100B to form a secondary molded body 102B serving as the other part of the frame 102 by injection molding. Thus, the primary molded body 102A and the secondary molded body 102B are integrally connected to form the frame 102, whereby the electrode-membrane-frame assembly is produced.